When testing biochemical components such as cells or bacterial spores the substances of interest (e.g. DNA, RNA, haemoglobin, protein etc.) must be extracted from said cells or spores in which they are contained and thus shielded from direct access by chemicals, enzymes or direct measurement. The method of disrupting cell membranes or bacterial spore walls is known as lysing. One method of lysing is to apply a lysing agent, capable of chemically breaking open or dissolving said membrane or wall. Other methods involve mechanical methods like grinding (e.g. “French press”) or repeated steps of freezing and thawing where crystallisation will cause physical rupture of cell walls.
One common method of lysing is that of sonication. Sonication involves exposing cells or spores in suspension to ultrasound. The liquid media (most often aqueous) in which cells or spores are suspended will act as a carrier of ultrasonic energy. If the pressures involved are of a substantial magnitude, cavitation in the liquid will occur. Cavitation involves the formation—respectively collapse, of high-pressure micro bubbles. The formation and subsequent collapse of micro bubbles will cause disrupting shear forces in the liquid media and as such around the cells or spores contained herein, ultimately breaking open membranes and walls and freeing the contents.